Speaking at the protest, she said: "I think [fans of the show] should sign the petition calling on President Obama to reopen the case, send letters to the boys in jail, to give them hope and cheer them up and do all they can to bring attention to the wider public."

She even wrote personally to both Avery and Dassey after watching the show, and joined protesters today - many of whom donned orange jumpsuits in a sign of solidarity with the pair.

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Across 10 episodes, Making a Murderer follows the plight of Avery, a Wisconsin man released after serving 18 years in prison for a rape that DNA ­evidence later proved he did not commit.

However after returning to his family, who run a scrapyard in the sticks and trying to rebuild his life, the roof caves in again.

Days before his lawyers are due to take crucial statements to support his £24million lawsuit against the local police and county prosecutors, he was accused of another terrible crime – the murder of a young photographer.

His then 16-year-old nephew Brendan was also jailed for life after confessing raping Teresa at his uncle’s request before the two killed her and set fire to her body.

Defence lawyers have argued Brendan’s confession to police officers Special Agent Tom Fassbender and Sgt Mark Wiegert should not have been admissible in court because he was vulnerable and there was no solicitor or parent present.

(Image: Getty)

Protesters first gathered outside the US Embassy in London before heading to Parliament Square.

Previously, Mrs Margolyes said: "Nothing about this case stacks up, absolutely nothing, it is absolutely sickening to watch what has gone on here, in fact I would go as far as to say it is utterly wicked.

"I am not a lawyer in anyway and I have watched the show like everyone else but I can truthfully say I think the whole thing is absolutely sinister.

"The Avery family have been a victim of the class system from start to finish, it is clear they have been treated like they were trash and by a group of people who were, in my opinion, colluding."